JP3786858B2 - Optical waveguide and method for manufacturing the same - Google Patents

Description

【００６５】
ただし、ｎは２以上の整数であり、Ｒ^１，Ｒ^２はそれぞれ炭素数１〜１０の置換もしくは非置換のアルキル、アルケニル、アリールあるいはシアノアルキル基であり、モル比で全体の４０％以下がビニル、フェニル、ハロゲン化フェニルである。また、Ｒ^１、Ｒ^２がメチル基のものが表面エネルギーが最も小さくなるので好ましく、モル比でメチル基が６０％以上であることが好ましい。また、鎖末端もしくは側鎖には、分子鎖中に少なくとも１個以上の水酸基等の反応性基を有する。
【００６６】
また、上記のオルガノポリシロキサンとともに、ジメチルポリシロキサンのような架橋反応をしない安定なオルガノシリコン化合物をバインダに混合してもよい。
【００６７】
本発明の光導波路においては、このようにオルガノポリシロキサン等の種々のバインダを光触媒含有層に用いることができる。本発明においては、上述したように、このようなバインダおよび光触媒を含む光触媒含有層にフッ素を含有させ、エネルギーをパターン照射することにより光触媒含有層表面のフッ素を低減させ、これにより撥液性領域内に親液性領域を形成するようにしてもよい。この際、光触媒含有層中にフッ素を含有させる必要があるが、このようなバインダを含む光触媒含有層にフッ素を含有させる方法としては、通常高い結合エネルギーを有するバインダに対し、フッ素化合物を比較的弱い結合エネルギーで結合させる方法、比較的弱い結合エネルギーで結合されたフッ素化合物を光触媒含有層に混入させる方法等を挙げることができる。このような方法でフッ素を導入することにより、エネルギーが照射された場合に、まず結合エネルギーが比較的小さいフッ素結合部位が分解され、これによりフッ素を光触媒含有層中から除去することができるからである。
【００６８】
上記第１の方法、すなわち、高い結合エネルギーを有するバインダに対し、フッ素化合物を比較的弱い結合エネルギーで結合させる方法としては、上記オルガノポリシロキサンにフルオロアルキル基を置換基として導入する方法等を挙げることができる。
【００６９】
例えば、オルガノポリシロキサンを得る方法として、上記（１）として記載したように、ゾルゲル反応等によりクロロまたはアルコキシシラン等を加水分解、重縮合して大きな強度を発揮するオルガノポリシロキサンを得ることができる。ここで、この方法においては、上述したように上記一般式：
Ｙ_ｎＳｉＸ_{（４−ｎ）}
（ここで、Ｙはアルキル基、フルオロアルキル基、ビニル基、アミノ基、フェニル基またはエポキシ基を示し、Ｘはアルコキシル基、アセチル基またはハロゲンを示す。ｎは０〜３までの整数である。）
で示される珪素化合物の１種または２種以上を、加水分解縮合物もしくは共加水分解縮合することによりオルガノポリシロキサンを得るのであるが、この一般式において、置換基Ｙとしてフルオロアルキル基を有する珪素化合物を用いて合成することにより、フルオロアルキル基を置換基として有するオルガノポリシロキサンを得ることができる。このようなフルオロアルキル基を置換基として有するオルガノポリシロキサンをバインダとして用いた場合は、エネルギーが照射された際、光触媒含有層中の光触媒の作用により、フルオロアルキル基の炭素結合の部分が分解されることから、光触媒含有層表面にエネルギーを照射した部分のフッ素含有量を低減させることができる。
【００７０】
この際用いられるフルオロアルキル基を有する珪素化合物としては、フルオロアルキル基を有するものであれば特に限定されるものではないが、少なくとも１個のフルオロアルキル基を有し、このフルオロアルキル基の炭素数が４から３０、好ましくは６から２０、特に好ましくは６から１６である珪素化合物が好適に用いられる。このような珪素化合物の具体例は上述した通りであるが、中でも炭素数が６から８であるフルオロアルキル基を有する上記珪素化合物、すなわちフルオロアルキルシランが好ましい。
【００７１】
本発明においては、このようなフルオロアルキル基を有する珪素化合物を上述したフルオロアルキル基を有さない珪素化合物と混合して用い、これらの共加水分解縮合物を上記オルガノポリシロキサンとして用いてもよいし、このようなフルオロアルキル基を有する珪素化合物を１種または２種以上用い、これらの加水分解縮合物、共加水分解縮合物を上記オルガノポリシロキサンとして用いてもよい。
【００７２】
このようにして得られるフルオロアルキル基を有するオルガノポリシロキサンにおいては、このオルガノポリシロキサンを構成する珪素化合物の内、上記フルオロアルキル基を有する珪素化合物が０．０１モル％以上、好ましくは０．１モル％以上含まれていることが好ましい。
【００７３】
フルオロアルキル基がこの程度含まれることにより、光触媒含有層上の撥液性を高くすることができ、エネルギーを照射して親液性領域とした部分との濡れ性の差異を大きくすることができるからである。
【００７４】
また、上記（２）に示す方法では、撥水牲や撥油性に優れた反応性シリコーンを架橋することによりオルガノポリシロキサンを得るのであるが、この場合も同様に、上述した一般式中のＲ^１，Ｒ^２のいずれかもしくは両方をフルオロアルキル基等のフッ素を含有する置換基とすることにより、光触媒含有層中にフッ素を含ませることが可能であり、またエネルギーが照射された場合に、シロキサン結合より結合エネルギーの小さいフルオロアルキル基の部分が分解されるため、エネルギー照射により光触媒含有層表面におけるフッ素の含有量を低下させることができる。
【００７５】
一方、後者の例、すなわち、バインダの結合エネルギーより弱いエネルギーで結合したフッ素化合物を導入させる方法としては、例えば、低分子量のフッ素化合物を導入させる場合は、例えばフッ素系の界面活性剤を混入する方法等を挙げることができ、また高分子量のフッ素化合物を導入させる方法としては、バインダ樹脂との相溶性の高いフッ素樹脂を混合する等の方法を挙げることができる。
【００７６】
本発明において光触媒含有層には上記の光触媒、バインダの他に、界面活性剤を含有させることができる。具体的には、日光ケミカルズ（株）製ＮＩＫＫＯＬＢＬ、ＢＣ、ＢＯ、ＢＢの各シリーズ等の炭化水素系、デュポン社製ＺＯＮＹＬ ＦＳＮ、ＦＳＯ、旭硝子（株）製サーフロンＳ−１４１、１４５、大日本インキ化学工業（株）製メガファックＦ−１４１、１４４、ネオス（株）製フタージェントＦ−２００、Ｆ２５１、ダイキン工業（株）製ユニダインＤＳ−４０１、４０２、スリーエム（株）製フロラードＦＣ−１７０、１７６等のフッ素系あるいはシリコーン系の非イオン界面活性剤を挙げることかでき、また、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤を用いることもできる。
【００７７】
また、光触媒含有層には上記の界面活性剤の他にも、ポリビニルアルコール、不飽和ポリエステル、アクリル樹脂、ポリエチレン、ジアリルフタレート、エチレンプロピレンジエンモノマー、エポキシ樹脂、フェノール樹脂、ポリウレタン、メラミン樹脂、ポリカーボネート、ポリ塩化ビニル、ポリアミド、ポリイミド、スチレンブタジエンゴム、クロロプレンゴム、ポリプロピレン、ポリブチレン、ポリスチレン、ポリ酢酸ビニル、ポリエステル、ポリブタジエン、ポリベンズイミダゾール、ポリアクリルニトリル、エピクロルヒドリン、ポリサルファイド、ポリイソプレン等のオリゴマー、ポリマー等を含有させることができる。
【００７８】
光触媒含有層中の光触媒の含有量は、５〜６０重量％、好ましくは２０〜４０重量％の範囲で設定することができる。また、光触媒含有層の厚みは、光触媒含有層が下部クラッド層として作用するために、０．１〜１μｍの範囲内が好ましく、特に好ましくは、０．１〜０．５μｍの範囲内である。
【００７９】
上記光触媒含有層は、光触媒とバインダを必要に応じて他の添加剤とともに溶剤中に分散して塗布液を調製し、この塗布液を塗布することにより形成することができる。使用する溶剤としては、エタノール、イソプロパノール等のアルコール系の有機溶剤が好ましい。塗布はスピンコート、スプレーコート、ディップコート、ロールコート、ビードコート等の公知の塗布方法により行うことができる。バインダとして紫外線硬化型の成分を含有している場合、紫外線を照射して硬化処理を行うことにより光触媒含有層を形成することができる。
【００８０】
（コア層）
一般に光導波路において、コア層はその内部を光が伝送するため、コア層の周囲を覆うクラッド層よりも屈折率が高いことが要求される。さらにコア層内部を導波する光が滞りなく伝送されるため、コア層の周辺部は整った形状であることが好ましい。コア層の周辺部が整った形状であることにより、コア層とこれに接する上部クラッド層との界面が整っていないことによる光伝送損失を防止することができるからである。
【００８１】
本発明においては、上述した一般的な光導波路のクラッド層に、上部クラッド層および光触媒含有層が該当する。したがって、コア層はこの両方の層よりも屈折率を高くすることが必要である。本発明におけるコア層の屈折率は、光触媒含有層上に付着させるコア層形成用材料を変化させることにより容易に調節することが可能であり、上部クラッド層および光触媒含有層との関係において、容易に好適な屈折率のコア層とすることができる。
【００８２】
さらに、本発明においては、光触媒含有層に対するエネルギー照射により生じる親液性および撥水性の濡れ性の違いを利用してコア層を形成するものである。つまりコア層を形成するコア層形成用材料は、親液性領域および撥水性領域に対する密着性に格段の違いを有するため、この性質を利用することにより、親液性領域にのみコア層形成用材料を付着させることが可能である。したがって、コア層の周辺部が整った形状となるため、コア層とこれに接する上部クラッド層との界面が整っていないことによる光伝送損失を防止することが可能である。
【００８３】
このようなコア層を形成するするための材料としては、ポリイミド、ポリカーボネート、ポリメタクリル酸メチル、ポリスチレン、酸化ケイ素等が挙げられる。これらの材料をスピンコート法やディップコート法等の各種コーティング法やインクジェット法等のノズル吐出法、蒸着法および無電解メッキ法等を材料の特性に応じて選択し、コア層を形成する。また選択する材料の種類や混合比率により屈折率を制御することが可能である。
【００８４】
また、光導波路においてコア層内における光の導波を良好に保つためにコア層の屈折率をその表面を被覆するクラッド層の屈折率よりも高くする必要がある。本発明においては、コア層の屈折率を１．１〜１．７の範囲内、好ましくは１．４〜１．７の範囲内とすることが好ましい。さらにコア層の表面を覆う上部クラッド層が透明性を有する材料で形成されている場合、コア層との屈折率差を０．０３以上、特に０．０５以上とすることが好ましい。コア層と上部クラッド層との屈折率差を上記範囲とし、かつコア層の下部を被覆する光触媒含有層とコア層との屈折率差を上述した範囲内とすることにより、光伝送損失の少ない光導波路の作製が可能となる。
【００８５】
ここでコア層の形状に関しては、通常コア層内を導波する光のモード等を考慮して決定する。導波光としては、一般に赤外光を用いることから、コア層の頂部から底部までの膜厚が、０．８〜３００μｍの範囲内、好ましくは１〜１００μｍの範囲内が好ましい。またコア層底部の幅は０．８〜３００μｍの範囲内、好ましくは１〜１００μｍの範囲内が好ましい。上記範囲内のコア層とすることにより、コア層内を滞りなく光が導波し、効率の良好な光導波路を得ることができるからである。
【００８６】
（上部クラッド層）
本発明のおいて、図１に示すように上部クラッド層５はコア層４の表面を被覆するように形成されている。図１に図示された上部クラッド層５は光触媒含有層２上の全面に形成されているが、コア層表面を被覆するようにパターン状に形成された上部クラッド層であってもよい。また光導波路におけるクラッド層の役割としては、光導波路の光伝送損失を抑制することの他に、外部からの応力等による悪影響の防止や、光導波路端面を切断して端面研磨する際、高い寸法精度の加工を可能とすること等を挙げることができる。
【００８７】
本発明において上部クラッド層は、透明性を有する材料で形成されている場合と、不透明である場合とのいずれの態様であってもよい。
【００８８】
まず、上部クラッド層が透明性を有する材料で形成されている場合について説明する。
【００８９】
上部クラッド層が透明性を有する材料で形成されている場合に用いられる材料としては、例えば、シリコン樹脂、ポリメタクリレート樹脂、ポリカーボネート樹脂、酸化珪素、ＵＶ硬化型エポキシ樹脂、エポキシ樹脂、フッ素化ポリイミド、ポリイミド、ポリカーボネイト―ＭＭＡ、重水素化ポリフルオロメタクリレート等を挙げることができる。
【００９０】
これらの材料は例えば蒸着法等により付着させることも可能であるが、好ましくはスピンコート、スプレーコート、ディップコート、ロールコート、ビードコート等の各種コーティング法やインクジェットなどの吐出法等により、塗工液とした上記材料を塗布することによって上部クラッド層を形成する。また選択する材料の種類や材料の混合比率によって屈折率を容易に変化させることができるため、コア層の屈折率に応じて屈折率差を制御した上部クラッド層の形成が可能である。
【００９１】
本発明において上部クラッド層の屈折率は１．１〜１．７の範囲内、好ましくは１．４〜１．７の範囲内であることが好ましい。上部クラッド層を上記範囲内とすることにより、光伝送損失の一要因である吸収損失を効果的に防止することができるからである。
【００９２】
また、上部クラッド層とコア層との屈折率の差は、０．０３以上、特に０．０５以上であることが好ましい。上記範囲程度にコア層の屈折率が上部クラッド層の屈折率よりも高ければ、吸収損失による光伝送損失を効率よく防止でき伝送効率の良好な光導波路が製造できるからである。
【００９３】
ところで、上述したように、本発明においては上部クラッド層の形状は、光触媒含有層上の全面に形成されている場合と、コア層表面を被覆するようにパターン状に形成されている場合とがある。
【００９４】
上部クラッド層が図１に図示するように、光触媒含有層上の全面に形成されている場合は、比較的製造が容易であるという利点を有する。さらに、上部クラッド層が光触媒含有層上の全面に形成されており、かつ透明性を有する場合、コア層頂部から上部クラッド層表面までの上部クラッド層の膜厚が、０．５〜３００μｍの範囲内、その中でも特に１〜１００μｍの範囲内であることが好ましい。この膜厚が上記範囲よりも薄くなるとコア層を導波する光の損失が顕著に大きくなり、光導波路として機能しなくなるからである。
【００９５】
一方、上部クラッド層が光触媒含有層上のコア層を被覆するようにパターン状に形成されていてもよい。このように上部クラッド層をパターン状に形成することにより、平面基板上に複雑な光配線を施し、分岐、スイッチィング、コネクト等の光インターコネクション機能を有する平面光導波路を、低損失にて、容易に作製できるといった利点を有するからである。
【００９６】
さらに、上部クラッド層がパターン状に形成され、かつ透明性を有する材料で形成されている場合、コア層の頂部から上部クラッド層の頂部までの上部クラッド層の膜厚は０．５〜３００μｍの範囲内、その中でも特に１〜１００μｍの範囲内であることが好ましい。またこの場合上部クラッド層はコア層の両側部に所定の幅を持つように形成されており、コア層の側部から上部クラッド層の側部までの上部クラッド層の幅は０．５〜３００μｍの範囲内、その中でも特に１〜１００μｍの範囲内であることが好ましい。上記範囲内の膜厚および幅で形成されている上部クラッド層であれば、コア層内を導波する光を反射させ、コア層を表面からの塵や汚れから防御し、外部からの応力等からの影響を防止するクラッド層としての機能を十分に発揮することができるからである。
【００９７】
次に、上部クラッド層が不透明な場合について説明する。この場合、上記上部クラッド層とコア層との界面が鏡面として作用する金属からなることが好ましい。このような金属として具体的には、金、アルミニウム、銅、銀等を挙げることができ、本発明においてはその中でも特にアルミニウムが好ましい。これらの金属を蒸着法等を用いて形成し、上部クラッド層とすることにより、上部クラッド層とコア層との界面が鏡面として作用し、コア層内を導波する光を全反射させるため、上部クラッド層への光の吸収損失が抑えられ、光伝送損失の少ない効率的な光導波路が得られるからである。
【００９８】
また、上部クラッド層の形状に関しては、コア層および上部クラッド層との界面で、隙間なく両者が接していればその界面における鏡面効果は十分に得ることができる。したがって、上部クラッド層が全面形成されている場合の上述した膜厚や、上部クラッド層がパターン状に形成されている場合の上述した膜厚および幅は、この鏡面効果に影響を及ぼさないため、上部クラッド層が不透明である場合は、これらの膜厚および幅は光の全反射に不都合がない程度であればよい。
【００９９】
（基板）
本発明において、基板は支持体としての役割を担う他、外部からの応力によるコア層への影響を和らげる働きも持つ。このような働きを担う材料であれば特に限定されないが、具体的には、ソーダガラス、石英ガラス、光学ガラス、無アルカリガラス等のガラス基板およびポリカーボネート、メチルメタクリレート単重合体または共重合体、ポリエチレンテレフタレート、ポリスチレン等のプラスチックフィルム、プラスチックシートなどを挙げることができる。
【０１００】
B．光導波路の製造方法について
本発明の光導波路の製造方法は、基板を準備する工程と、上記基板上に少なくとも光触媒とバインダとを有しエネルギー照射により照射部分の濡れ性が液体との接触角が低下する方向に変化する光触媒含有層を形成する工程と、上記光触媒含有層上のコア層を形成する部位であるコア層形成部に、エネルギーをパターン照射してコア層露光部を形成する工程と、上記光触媒含有層のコア層露光部上にコア層を形成する工程と、上記光触媒含有層上に形成された上記コア層の表面を被覆するように上部クラッド層を形成するために、上記光触媒含有層上の上部クラッド層が形成される部位である上部クラッド層形成部に、エネルギーを照射して上部クラッド層露光部を形成する工程と、上記上部クラッド層露光部上に上部クラッド層を形成する工程とを有するものである。
【０１０１】
本発明においては、このような製造方法とすることにより、図３に図示した従来の光導波路の製造方法よりも、コア層のパターニングにかかる手間を簡略化することが可能であるという利点を有する。
【０１０２】
図２は、本発明の光導波路の製造方法の一例を示す工程図である。まずこの図２の各工程について説明する。
【０１０３】
図２の（ａ）に示すように、基板１を準備し、準備された基板１上に少なくとも光触媒とバインダとからなる光触媒含有層の形成材料を溶剤に溶かした塗工液を塗布し、乾燥させ光触媒含有層２を形成する（光触媒含有層形成工程）。
【０１０４】
次いで、上記光触媒含有層２上のコア層４を形成する部位であるコア層形成部以外にマスク６をかけ、エネルギー７がコア層形成部にのみ照射されるようにパターン照射し（図２（ｂ））、上記パターン照射によるエネルギー照射領域であるコア層露光部３を形成する（コア層露光部形成工程）（図２（ｃ））。
【０１０５】
さらに、上記光触媒含有層２のコア層露光部３上にコア層形成用材料を付着させ、乾燥させることによりコア層４を形成する（コア層形成工程）（図２（ｄ））。
【０１０６】
上記光触媒含有層２上に形成された上記コア層４の表面を被覆するように上部クラッド層５を形成するため、上記光触媒含有層２上の上部クラッド層５が形成される部位である上部クラッド層形成部に、エネルギーを照射することにより（図２（ｆ））、図２（ｅ）に示すように、上部クラッド層露光部８が形成される（上部クラッド層露光部形成工程）。
【０１０７】
そして、上記上部クラッド層露光部８上に上部クラッド層形成材料を付着させ、乾燥させることによって上部クラッド層５を形成する（上部クラッド層形成工程）（図２（ｅ））。
【０１０８】
以下、このような各工程について詳細に説明をする。
【０１０９】
（光触媒含有層形成工程）
まず、第１の工程である光触媒含有層を設ける工程について説明する。光触媒含有層形成工程とは、基板上に少なくとも光触媒とバインダとを有しエネルギー照射により照射部分の濡れ性が液体との接触角が低下する方向に変化する光触媒含有層を形成する工程である。
【０１１０】
この光触媒含有層の形成は、上述したような光触媒とバインダとを必要に応じて他の添加剤とともに溶剤中に分散させた塗布液を調製し、この塗布液を塗布した後、加水分解、重縮合反応を進行させてバインダ中に光触媒を強固に固定することにより形成される。使用する溶剤としては、エタノール、イソプロパノール等のアルコール系の有機溶剤が好ましく、塗布はスピンコート、スプレーコート、ディップコート、ロールコート、ビードコート等の公知の塗布方法により行うことができる。また、結合剤として、紫外線硬化型の成分を含有している場合には、紫外線を照射して硬化処理を行うことにより、基材上に光触媒含有層を形成することができる。
【０１１１】
（コア層露光部形成工程）
次に第２の工程であるコア層露光部の形成工程について説明する。このコア層露光部形成工程とは、上記光触媒含有層上のコア層を形成する部位であるコア層形成部に、エネルギーをパターン照射してコア層露光部を形成する工程である。
【０１１２】
本発明において照射されるエネルギーとしては、光触媒含有層の濡れ性を変化させるエネルギーであればいかなるエネルギーでも使用可能であるが、中でも光を用いることが好ましい。光は制御しやすく、安全に操作することが可能であるからである。
【０１１３】
さらに、本発明において用いられる光触媒の触媒反応を起こさせる光の波長を考慮して選択された光を用いることが好ましい。例えば、硫化カドニウムであれば４９６ｎｍ、また酸化鉄であれば５３９ｎｍの可視光であり、二酸化チタンであれば３８８ｎｍの紫外光である。このように、用いる光触媒に対応して、光であれば可視光であれ紫外光であれ用いることができるのであるが、上述したようにバンドギャップエネルギーが高いため光触媒として有効であり、かつ化学的にも安定で毒性もなく、入手も容易といった理由から光触媒としては二酸化チタンが好適に用いられる関係上、この二酸化チタンの触媒反応を開始させる紫外光を含む光であることが好ましい。具体的には、４００ｎｍ以下の範囲、好ましくは３８０ｎｍ以下の範囲の紫外光が含まれることが好ましい。
【０１１４】
このような紫外光を含む光の光源としては、水銀ランプ、メタルハライドランプ、キセノンランプ、エキシマランプ等の種々の紫外線光源を挙げることができる。また、露光に際しての光の照射量は、露光された部位が光触媒の作用により親液性を発現するのに必要な照射量とすることができる。
【０１１５】
エネルギーの照射に際してパターン照射が必要な場合は、上述したような光源を用い、フォトマスクを介したパターン照射により行うことができるが、他の方法として、エキシマ、ＹＡＧ等のレーザーを用いてパターン状に描画照射する方法を用いることも可能である。
【０１１６】
なお、このコア層露光部が形成される部位等の詳細については、Ａ．光導波路についての（コア層）の項目において、説明したとおりなのでここでの説明は省略する。
【０１１７】
（コア層形成工程）
次に第３の工程であるコア層形成工程について説明する。このコア層形成工程は、上記光触媒含有層のコア層露光部上にコア層を形成する工程である。
【０１１８】
このコア層形成工程において、コア層露光部にコア層を形成するために、コア層形成用材料をコア層露光部上に付着させる方法がとられる。この方法としてはコーティング法、吐出法、蒸着法、無電解メッキ法等があるが、この中でも塗工液を用いるコーティング法および吐出法が好ましい。
【０１１９】
具体的には、上記コア層形成用材料を溶剤中に分散してコア層形成用塗工液を調製し、このコア層形成用塗工液を上記コア層露光部上に塗布した後、硬化させることによりコア層を形成する方法等を挙げることができる。さらにこの塗工液を用いる方法の中でも、効率よくコア層形成用塗工液を塗布できるという観点から、ノズル吐出法が好ましい。ノズル吐出法であればコア層形成用塗工液の塗布位置が正確であり、發液性の領域に残存するコア層形成用塗工液の量を抑えることができるからである。さらにこのノズル吐出法の中でもインクジョット法が好適に用いられる。これは、量産可能であるためコスト面で有利である等の理由によるものである。
【０１２０】
このコア層形成用材料を溶解させる溶剤としては、コア層形成用材料が溶解可能であり、かつ光触媒含有層のエネルギー露光部とエネルギー未露光部との接触角の差が２０°以上となる溶剤であれば特に限定されない。特にＮ−メチル−２−ピロリドン、シクロヘキサノンおよびこれらを含む混合溶液が好ましい。また、結合剤として、紫外線硬化型の成分を含有している場合には、紫外線を照射して硬化処理を行うことにより、光触媒含有層のコア層露光部上にコア層を形成することができる。
【０１２１】
（上部クラッド層露光部形成工程および上部クラッド層形成工程）
上部クラッド層露光部形成工程とは、上記光触媒含有層上に形成された上記コア層の表面を被覆するように上部クラッド層を形成するために、上記光触媒含有層上の上部クラッド層が形成される部位である上部クラッド層形成部に、エネルギーを照射して上部クラッド層露光部を形成する工程である。
【０１２２】
さらに上部クラッド層形成工程とは、上記上部クラッド層露光部上に上部クラッド層を形成する工程である。
【０１２３】
本発明において、この上部クラッド層露光部形成工程および上部クラッド層形成工程の一連の工程は、大きく２つの実施態様に分けることができる。第１の実施態様は上部クラッド層が透明性を有する材料で形成されている態様である。さらに第２の実施態様は上部クラッド層が不透明である場合である。以下に両実施態様について各工程毎に説明する。
【０１２４】
ａ．第１実施態様
第１実施態様は上部クラッド層が透明性を有する材料で形成されている態様である。さらにこの第１実施態様の中でも上部クラッド層の形状の違いから、
上部クラッド層がコア層を被覆するように光触媒含有層上の全面に形成されている場合
上部クラッド層がコア層の表面のみを覆うようにパターン状に形成されている場合
に分けることができる。
【０１２５】
以下に、第１実施態様を（１）、（２）の各場合について説明を行う。
【０１２６】
（１） 上部クラッド層がコア層を被覆するように光触媒含有層上の全面に形成されている場合
まず、上部クラッド層がコア層を被覆するように光触媒含有層上の全面に形成されている場合について説明を行う。
【０１２７】
具体的には、上記上部クラッド層露光部形成工程が、この場合においては、上記光触媒含有層の表面に対して全面にエネルギーを照射して、上部クラッド層露光部を形成する工程（上部クラッド層露光部全面形成工程）となり、上記上部クラッド層形成工程が、上記上部クラッド層露光部上にコア層を被覆するように全面に、上部クラッド層を形成する工程（上部クラッド層全面形成工程）となる。
【０１２８】
以下に両工程ついて説明をする。
【０１２９】
（上部クラッド層露光部全面形成工程）
上部クラッド層露光部全面形成工程は、上記コア層形成工程により、光触媒含有層上の所望の位置にコア層が形成された上記光触媒含有層上の全面にエネルギーを照射する工程である。このエネルギー照射により上記光触媒含有層上のうち上記コア層が形成されている部位以外の表面はすべて親液性となり、この親液性領域が上部クラッド層全面露光部となる。その他エネルギー照射等に関することは、上記コア層露光部形成工程の中で説明したとおりなので、ここでの説明は省略する。
【０１３０】
（上部クラッド層全面形成工程）
上部クラッド層全面形成工程は、上記上部クラッド層露光部全面形成工程により形成された上部クラッド層全面露光部上に上部クラッド層形成用材料を付着させ、上記光触媒含有層上の全面に上部クラッド層を形成する工程である。
【０１３１】
このような上部クラッド層形成用材料を上部クラッド層全面露光部上に付着させる方法としては、コーティング法、吐出法、蒸着法、無電解メッキ法等があるが、この中でも塗工液を用いるコーティング法および吐出法が好ましい。
【０１３２】
具体的には、上記上部クラッド層形成用材料を溶剤中に分散して上部クラッド層形成用の塗工液を調製し、この塗工液を上記上部クラッド層全面露光部上に塗布した後、硬化させることによりコア層を形成する方法等が挙げられる。
【０１３３】
ここで、この上部クラッド層形成用材料を溶解させる溶剤としては、上部クラッド層形成用材料が溶解可能であり、かつ光触媒含有層のエネルギー露光部とエネルギー未露光部との接触角の差が２０°以上となる溶剤であれば特に限定されない。特にＮ−メチル−２−ピロリドン、シクロヘキサノンおよびこれらを含む混合溶液が好ましい。
【０１３４】
また、結合剤として、紫外線硬化型の成分を含有している場合には、紫外線を照射して硬化処理を行うことにより、光触媒含有層上の全面に上部クラッド層を形成することができる。
【０１３５】
（２） 上部クラッド層がコア層の表面のみを覆うようにパターン状に形成されている場合
次に、上部クラッド層が透明性を有する材料で形成されており、かつコア層の表面を覆うようにパターン状に上部クラッド層が形成されている場合について説明する。
【０１３６】
この場合、具体的には、上記上部クラッド層露光部形成工程が、上記光触媒含有層の表面に対して、上記コア層の両側部に所定の幅を持つようにエネルギーをパターン照射して、上部クラッド層露光部を形成する工程（パターン状上部クラッド層露光部形成工程）となり、さらに上記上部クラッド層形成工程が、上記パターン状上部クラッド層露光部上に上記コア層を被覆するように、パターン状に上部クラッド層を形成する工程（パターン状上部クラッド層形成工程）となる。
【０１３７】
以下に両工程について説明する。
【０１３８】
（パターン状上部クラッド層露光部形成工程）
パターン状上部クラッド層露光部形成工程は、上記コア層形成工程により、所望の位置にコア層を有する上記光触媒含有層上にエネルギーをパターン照射する工程である。
【０１３９】
この工程は、コア層の側部から一定の幅までの領域の光触媒含有層に対し、エネルギーをパターン照射することにより、コア層の側部から一定の幅までの領域が、コア層を取り囲むように親液性領域となる。この親液性領域がパターン状上部クラッド層露光部である。その他、コア層側部から上部クラッド層側部までの幅やエネルギーの照射方法等に関しては、上述したとおりなのでここでの説明は省略する。
【０１４０】
（パターン状上部クラッド層形成工程）
パターン状上部クラッド層形成工程は、上記パターン状上部クラッド層露光部形成工程により形成された上記パターン状上部クラッド層露光部上に上部クラッド層を形成する工程である。
【０１４１】
このパターン状上部クラッド層形成工程においては、パターン状に上部クラッド層が形成される以外は、上記上部クラッド層全面形成工程と同様であるのでここでの詳細な説明は省略する。
【０１４２】
ｂ．第２実施態様
本発明における第２実施態様は、上部クラッド層が不透明な材料で形成された態様である。
【０１４３】
このように、上部クラッド層が不透明な材料で形成される場合の製造方法としては、上述したようにコア層と上部クラッド層との界面が鏡面として作用する必要性があることから、具体的には、蒸着法、スパッタ法、ＣＶＤ法、転写法、無電解メッキ法、溶解金属を用いたスプレーコート等によるコーティング法等を挙げることができ、中でも蒸着法による方法が好ましい。
【０１４４】
この場合は、コア層および上部クラッド層との界面において隙間なく金属が形成されてさえいれば、鏡面効果の作用による光の全反射が効率的に行われる。したがって、上述したように上部クラッド層が光触媒含有層上の全面に形成されている場合でも、またパターン状に形成されている場合でも、コア層と上部クラッド層との界面において隙間なく上部クラッド層が形成されてさえいれば、この鏡面効果による光の全反射は起こる。そこで鏡面効果を損なわせない程度に、上部クラッド層が不透明な場合に用いられる上述した金属を上述した方法によって形成することが好ましい。
【０１４５】
なお、本発明は、上記実施形態に限定されるものではない。上記実施形態は例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。
【０１４６】
【実施例】
以下に実施例を示し、本発明をさらに説明する。
【０１４７】
５０×１００ｍｍの無アルカリガラス基板上に光触媒を含有する光触媒含有層を形成し、紫外線を開口線幅１００μｍのラインパターンが施されたマスクパターンを介して照射することにより、光触媒含有層上に同ラインパターンに即した濡れ性の異なるパターンを形成した。
【０１４８】
このパターンを有する基板のエネルギー露光部である１００μｍのラインパターン形成部のディスペンサー方式にて、ポリメタクリル酸メチルのＮ−メチル−２−ピロリドン溶液を塗布したところ、エネルギー露光部のみに溶液は付着した。これを２５０℃にて３０分間乾燥することにより硬化させた。
【０１４９】
次にこの基板全体に対し紫外線露光を施し、ポリスチレンのシクロヘキサノン溶液を基板全面に塗布した。これを前述同様の乾燥方法にて硬化させることにより光損失３０ｄＢ／ｍ以下の光導波路を形成することができた。
【０１５０】
【発明の効果】
本発明によれば、光触媒含有層上のコア層形成部を予め親液性とし、液体との接触角の小さい親液性領域のみコア層形成用塗工液が付着することを利用して、所望の領域に精度よくコア層を作製することができるという効果を奏する。さらに本発明においては、コア層は光触媒含有層上に形成されていることから、コア層および光触媒含有層の屈折率差を調節することにより、光触媒含有層を上部クラッド層と同様の働きを担う下部クラッド層として活用することができる。したがって、別途クラッド層を形成する必要がなく、工程の簡略化が可能となり、コストを低減させることができるという効果を奏する。
【図面の簡単な説明】
【図１】本発明の光導波路の一例を示す概略断面図である。
【図２】本発明の光導波路の製造方法の一例を示す工程図である。
【図３】従来の光導波路の製造方法を示す工程図である。
【符号の説明】
１ … 基板
２ … 光触媒含有層
３ … コア層露光部
４ … コア層
５ … 上部クラッド層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical waveguide that can be easily manufactured by utilizing lyophilic and lyophobic patterning of a photocatalyst-containing layer.
[0002]
[Prior art]
With the rapid spread of the Internet today, commercial deployment of optical communication systems is proceeding at a great pace. As manufacturing methods and structures of optical waveguides used for such optical communication, the following are known.
[0003]
First, a method using an inorganic material such as quartz glass, multi-component glass, or inorganic crystal can be mentioned. This method requires a considerably high manufacturing temperature in order to form a transparent glass cladding layer, and it is not suitable for commercialization because it is impossible to form a large-area optical waveguide.
[0004]
Next, the manufacturing method using a polymeric material can be mentioned. A polymer material is easy to form a thin film on a substrate by a spin coating method, a dip coating method, or the like, and is suitable for manufacturing a large-area optical waveguide. Further, since the heat treatment process at a high temperature is not included in the film formation, it is possible to form an optical waveguide even on a substrate having poor heat resistance as compared with the above-described manufacturing method using an inorganic material such as quartz glass. In addition, flexible optical waveguides can be manufactured by taking advantage of the flexibility and toughness that are the characteristics of polymer materials. Therefore, optical waveguide components such as optical integrated circuits currently used in the field of optical communications and optical wiring boards used in the field of optical information communications are manufactured in large quantities and at low cost by a manufacturing method using such a polymer material. It is expected that.
[0005]
FIG. 3 shows a manufacturing method using the above-described polymer material, specifically, a manufacturing method for manufacturing an optical waveguide composed of a core layer and a cladding layer using a photolithography method. Hereinafter, FIG. 3 will be described in the order of steps.
[0006]
As shown in FIG. 3A, a polymer material for forming the lower cladding layer 32 is applied on the substrate 31 and dried to form the lower cladding layer 32. Next, as shown in FIG. 3B, the core layer forming layer 33 is formed by applying and curing a core layer forming coating solution on the lower clad layer 32. Further, a photoresist is applied on the core layer forming layer 33 and dried to form a photoresist layer 34. Next, in order to pattern the core layer forming layer 33 into a desired core layer, a position where the core layer is patterned is covered with a photomask 35, and ultraviolet rays 36 are irradiated through the photomask 35 (FIG. 3C). The region irradiated with the ultraviolet rays 36 in the photoresist layer 34 is removed by development and washing with a photoresist developer, and the photoresist layer is formed only on the upper part of the position where the core layer is formed as shown in FIG. Will be the remaining shape. The photoresist layer having this shape is referred to as a photoresist portion 34 '. When the exposed layer 33 of the core layer forming layer 33 is removed with a core layer developer, the core layer 33 ′ having a photoresist portion 34 ′ at the top is removed as shown in FIG. Is formed. Subsequently, when the photoresist portion 34 ′ remaining on the core layer 33 ′ is stripped with a photoresist stripping solution, the core layer 33 ′ is exposed as shown in FIG. Finally, a polymer material for forming the upper cladding layer 37 is applied on the lower cladding layer 32 having the core layer 33 ′, and the upper cladding layer 37 is formed in the same manner as the lower cladding layer 32. Through these steps, an optical waveguide as shown in FIG. 3G is completed.
[0007]
However, there are some problems in the manufacturing method using the photolithography method described above. First, because there are many manufacturing processes, it takes time to manufacture, and various high-accuracy equipments are required, resulting in high costs. Second, development and cleaning performed during patterning of the core layer The problem of waste liquid treatment in the process, and thirdly, the problem of optical transmission loss due to the irregularity of the interface between the core layer and the clad layer due to the limit of the patterning accuracy of the core layer.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and provides a higher-quality optical waveguide that is advantageous in terms of cost and is environmentally friendly as the manufacturing process is simplified. Is the main purpose.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, as described in claim 1, the wettability changes so that the contact angle between the substrate and the liquid formed on the substrate is reduced by energy irradiation. A photocatalyst-containing layer comprising at least a photocatalyst and a binder, a core layer formed in a pattern on the photocatalyst-containing layer, and an upper clad layer formed on the photocatalyst-containing layer so as to cover the core layer An optical waveguide characterized by the above is provided.
[0010]
If a photocatalyst containing layer that changes wettability is formed so that the contact angle with the liquid is reduced by energy irradiation, the wettability of the irradiated part is easily changed by performing energy pattern irradiation, and the liquid and The lyophilic region having a small contact angle can be obtained. Therefore, in the present invention, by utilizing such a method, the core layer forming part on the photocatalyst-containing layer is made lyophilic in advance, and only the lyophilic region having a small contact angle with the liquid is coated for forming the core layer. By utilizing the adhesion of the liquid, it is easy to accurately produce the core layer in a desired region. Furthermore, in the present invention, since the core layer is formed on the photocatalyst-containing layer, the photocatalyst-containing layer has the same function as the upper cladding layer by adjusting the refractive index difference between the core layer and the photocatalyst-containing layer. It can be used as a lower cladding layer. Therefore, it is not necessary to form a separate cladding layer, the process can be simplified, and the cost can be reduced.
[0011]
In the invention described in claim 1, as described in claim 2, the upper cladding layer is preferably formed in a pattern on the photocatalyst-containing layer. In this way, by forming the upper clad layer in a pattern, a complicated optical wiring is provided on the planar substrate, and a planar optical waveguide having optical interconnection functions such as branching, switching, and connection can be obtained with low loss. This is because it has an advantage that it can be easily manufactured.
[0012]
In the invention described in the first or second aspect, as described in the third aspect, the contact angle with the liquid having a surface tension of 40 mN / m on the photocatalyst containing layer is not irradiated with energy. Is preferably 10 degrees or more, and is preferably less than 10 degrees in the portion irradiated with energy.
[0013]
Since the portion not irradiated with energy is a portion that requires liquid repellency, when the contact angle with a liquid having a surface tension of 40 mN / m is less than 10 degrees, the liquid repellency is not sufficient, Since there is a possibility that the coating material for forming the core layer may remain, it is not preferable. Further, when the contact angle with the liquid with a surface tension of 40 mN / m in the portion irradiated with energy is 10 degrees or more, the spread of the coating material for forming the core layer in this portion may be inferior, and accurate patterning is performed. This is because it becomes difficult.
[0014]
In the invention described in any one of claims 1 to 3, as described in claim 4, a difference in refractive index between the photocatalyst-containing layer and the core layer is 0.03. The above is preferable. This is because if the difference in refractive index is smaller than the above range, it becomes difficult to guide light well in the core layer. Further, as described above, if there is a difference in refractive index within the above range, the photocatalyst-containing layer can be sufficiently utilized as a lower clad layer that performs the same function as the upper clad layer.
[0015]
In the invention described in any one of claims 1 to 4, when the upper cladding layer is formed of a transparent material as described in claim 5, The refractive index difference between the upper cladding layer and the core layer is preferably 0.03 or more. This is because when the refractive index difference between the upper cladding layer and the core layer is at least the above-mentioned range, the absorption loss of light from the core layer to the upper cladding layer can be suppressed.
[0016]
In the invention described in any one of claims 1 to 4, as described in claim 6, when the upper cladding layer is opaque, the upper cladding layer and the core layer It is preferable that the interface is made of a metal that acts as a mirror surface. By using a metal in which the interface between the opaque upper cladding layer and the core layer acts as a mirror surface in this way, an optical waveguide in which all the light from the core layer to the upper cladding layer is reflected and the loss of light is suppressed to the maximum extent is obtained. This is because it can be manufactured.
[0017]
In the invention described in any one of claims 1 to 6, as described in claim 7, the photocatalyst-containing layer contains fluorine, and the photocatalyst-containing layer is irradiated with energy. In this case, it is preferable that the photocatalyst-containing layer is formed so that the fluorine content on the surface of the photocatalyst-containing layer is lowered by the action of the photocatalyst as compared with that before energy irradiation.
[0018]
Thus, since the optical waveguide of the present invention is configured so that the fluorine content in the energy irradiation region of the photocatalyst-containing layer is reduced, the pattern is irradiated with the energy to reduce the fluorine content from the region. Pattern can be formed. When the fluorine content decreases, the region becomes a region having higher lyophilicity than other portions, so that only the portion where the core layer is formed can be easily made a lyophilic region. This is because the core layer can be formed only by applying the core layer forming coating solution to the liquid region.
[0019]
In the invention described in claims 1 to 7, as described in claim 8, the photocatalyst is titanium oxide (TiO 2).₂), Zinc oxide (ZnO), tin oxide (SnO)₂), Strontium titanate (SrTiO)₃), Tungsten oxide (WO₃), Bismuth oxide (Bi₂O₃), And iron oxide (Fe₂O₃It is preferable that it is 1 type, or 2 or more types of substances selected from these. Among them, as described in claim 9, titanium oxide (TiO₂) Is preferable. This is because titanium oxide is effective as a photocatalyst because of its high band gap energy, is chemically stable, has no toxicity, and is readily available.
[0020]
In the invention described in claims 1 to 9, as described in claim 10, the binder is Y_nSiX_(4-n)Wherein Y represents an alkyl group, a fluoroalkyl group, a vinyl group, an amino group, a phenyl group or an epoxy group, X represents an alkoxyl group or a halogen, and n is an integer from 0 to 3. It is preferable that it is the organopolysiloxane which is a 1 type, or 2 or more types of hydrolyzed condensate or cohydrolyzed condensate of the silicon compound. This is because by using such an organopolysiloxane, the photocatalyst can be strongly retained in the photocatalyst-containing layer even when energy is irradiated.
[0021]
In order to achieve the above object, according to the present invention, a process for preparing a substrate, and at least a photocatalyst and a binder are provided on the substrate, and the wettability of the irradiated portion is liquid by energy irradiation. A step of forming a photocatalyst-containing layer that changes in a direction in which the contact angle with the core decreases, and a core layer exposure part by irradiating the core layer forming part, which is a part for forming the core layer on the photocatalyst-containing layer, with a pattern Forming a core layer on the exposed portion of the core layer of the photocatalyst-containing layer, and forming an upper clad layer so as to cover the surface of the core layer formed on the photocatalyst-containing layer Therefore, a step of irradiating the upper clad layer forming part, which is a part where the upper clad layer on the photocatalyst-containing layer is formed, irradiating energy to form an upper clad layer exposed part, and the upper clad layer To provide a manufacturing method of the optical waveguide, characterized in that a step of forming an upper cladding layer on the optical unit.
[0022]
Comparing the optical waveguide manufacturing method according to the present invention with the above-described conventional optical waveguide manufacturing method shown in FIG. 3, first, the extra portions shown in FIGS. 3D to 3E The step of removing the core layer forming layer can be omitted, and the manufacturing process can be simplified. Further, in the present invention, the series of steps shown in FIGS. 3 (c) to 3 (f) irradiates the photocatalyst-containing layer with energy according to the pattern of the core layer to form a core layer exposed portion, By simply applying the coating solution for forming the core layer to the region, it is possible to expect a dramatic improvement in production efficiency. Further, in this series of steps shown in FIG. 3, there is an advantage that it is possible to solve the problem of the waste liquid generated when developing and washing the photoresist layer for patterning the core layer forming layer into a desired shape. It is done.
[0023]
In the invention described in claim 11, as described in claim 12, a step of forming an upper cladding layer exposed portion by the energy irradiation, and an upper cladding layer is formed on the upper cladding layer exposed portion. Forming a top clad layer exposure part by pattern irradiating the surface of the photocatalyst-containing layer with energy so as to have a predetermined width on both sides of the core layer; and the top clad layer And a step of forming an upper clad layer so as to cover the core layer on the exposed portion.
[0024]
Thereby, it is possible to form an upper clad layer that covers the core layer surface and is arranged in a pattern. As described above, by forming the upper cladding layer in a pattern, a complicated optical wiring is applied on the planar substrate, and a planar optical waveguide having optical interconnection functions such as branching, switching, and connection can be reduced in a low loss. This is because it has the advantage of being easily manufactured.
[0025]
In the invention described in claim 11, as described in claim 13, a step of forming an upper clad layer exposed portion by the energy irradiation, and an upper clad layer is formed on the upper clad layer exposed portion. Irradiating the entire surface of the photocatalyst-containing layer with energy to form an upper clad layer exposed portion, and an upper clad layer so as to cover a core layer on the upper clad layer exposed portion. It is preferable to have the process of forming. This is because the formation of the upper cladding layer on the entire surface of the photocatalyst-containing layer can be easily performed in the manufacturing process.
[0026]
In the invention described in any one of claims 11 to 13, as described in claim 14, the contact angle with a liquid having a surface tension of 40 mN / m on the photocatalyst-containing layer is It is preferable that the angle is not less than 10 degrees in the portion not irradiated with energy and less than 10 degrees in the portion irradiated with energy.
[0027]
As described above, the portion that is not irradiated with energy is a portion that requires liquid repellency. Therefore, when the contact angle with a liquid having a surface tension of 40 mN / m is less than 10 degrees, liquid repellency is obtained. Is not sufficient, and there is a possibility that the coating material for forming the core layer may remain. Further, when the contact angle with the liquid with a surface tension of 40 mN / m in the portion irradiated with energy is 10 degrees or more, the spread of the coating material for forming the core layer in this portion may be inferior, and accurate patterning is performed. This is because it becomes difficult.
[0028]
In the invention described in any one of claims 11 to 14, as described in claim 15, a core layer formed in a pattern on the photocatalyst-containing layer is a core. A core layer formed by applying a layer forming coating solution is preferred. In particular, it is preferable that the step of applying the core layer forming coating solution to form the core layer is applied by a nozzle discharge method. By applying by the nozzle discharge method, it becomes possible to efficiently apply the coating liquid for forming the core layer. In addition, the application position of the coating liquid for forming the core layer is accurate, and it is possible to suppress the amount of the coating liquid for forming the core layer that remains in the liquid-repellent region. This is because optical transmission loss due to interface irregularity at the interface between the layer and the upper cladding layer can be prevented.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. First, an optical waveguide will be described, and then a method for manufacturing the optical waveguide will be described.
[0030]
A. About optical waveguide
The optical waveguide of the present invention comprises a substrate, a photocatalyst-containing layer comprising at least a photocatalyst and a binder, wherein the wettability is changed so that a contact angle with a liquid is reduced by energy irradiation, and the photocatalyst is formed on the substrate. It has a core layer formed in a pattern on the containing layer and an upper clad layer formed on the photocatalyst containing layer so as to cover the core layer.
[0031]
FIG. 1 is a schematic cross-sectional view illustrating an example of an optical waveguide according to the present invention. The optical waveguide shown in FIG. 1 is provided in the photocatalyst-containing layer 2 formed on the substrate 1, the core layer exposure unit 3 that is an energy irradiation region on the photocatalyst-containing layer 2, and the core layer exposure unit 3. The core layer 4 formed in a pattern on the photocatalyst containing layer 2 and the upper clad layer 5 formed on the photocatalyst containing layer 2 so as to cover the core layer 4. The upper clad layer 5 shown in FIG. 1 is formed on the entire surface of the photocatalyst containing layer 2, but may be an upper clad layer formed in a pattern so as to cover only the surface of the core layer 4. .
[0032]
The optical waveguide plays a role of transmitting various information converted into light to other devices by light guiding in the core layer. Therefore, how to make an optical waveguide with a small optical transmission loss is an important factor. As a cause of this optical transmission loss, an interface irregularity due to the fact that the shape at the interface between the core layer and the clad layer is not uniformly arranged can be mentioned. In the present invention, by utilizing the lyophilic and lyophobic pattern of the photocatalyst-containing layer, the interface irregularity is caused by attaching a core layer-forming coating solution exhibiting good adhesion to the lyophilic region. Since it is possible to prevent the formation of a core layer having a desired shape, it is possible to manufacture an optical waveguide with high accuracy. Hereinafter, the optical waveguide of the present invention will be described in detail for each configuration.
[0033]
(Photocatalyst containing layer)
In the optical waveguide of the present invention, the contact angle with the liquid is lowered by exposure (in the present invention, not only light is irradiated but also energy is irradiated). It is possible to form a pattern of a lyophilic region having a small contact angle with a liquid by providing a photocatalyst-containing layer that changes in wettability, and easily changing the wettability by performing energy pattern irradiation or the like on the layer. . As a result, only the region where the core layer is formed can be easily made a lyophilic region. Further, the photocatalyst-containing layer can be used as a lower clad layer having the same function as the upper clad layer by adjusting the difference in refractive index between the core layer and the photocatalyst-containing layer. As a result, an optical waveguide having an efficient manufacturing process and advantageous in terms of cost can be easily obtained. In this case, light containing ultraviolet light is usually used as energy.
[0034]
Here, the lyophilic region is a region having a small contact angle with the liquid, and refers to a region having good wettability with respect to the coating solution for forming the core layer. Further, the liquid repellent region is a region having a large contact angle with the liquid and means a region having poor wettability with respect to the coating liquid for forming the core layer.
[0035]
In the unexposed portion, the photocatalyst-containing layer has a contact angle with a liquid with a surface tension of 40 mN / m of 10 degrees or more, preferably a contact angle with a liquid with a surface tension of 30 mN / m of 10 degrees or more, particularly a surface The contact angle with a liquid having a tension of 20 mN / m is preferably 10 degrees or more. This is because the unexposed part is a part that requires liquid repellency in the present invention. Therefore, when the contact angle with the liquid is small, the liquid repellency is not sufficient and the core layer forming coating is not. This is because the remaining of the working fluid or the like in the liquid repellent region may cause problems such as difficulty in making the shape of the side portion of the core layer and the like into a good state.
[0036]
In addition, the photocatalyst-containing layer has a contact angle with a liquid that decreases when exposed to light, and a contact angle with a liquid with a surface tension of 40 mN / m is less than 10 degrees, preferably a liquid with a surface tension of 50 mN / m. It is preferable that the layer has a contact angle with a liquid of 10 degrees or less, particularly a surface tension of 60 mN / m, of 10 degrees or less. This is because if the contact angle of the exposed portion with the liquid is high, the spread of the coating liquid for forming the core layer in this portion may be inferior, and accurate patterning becomes difficult.
[0037]
In addition, the contact angle with the liquid here is measured using a contact angle measuring instrument (Kyowa Interface Science Co., Ltd. CA-Z type) with a liquid having various surface tensions (from the microsyringe to the liquid. 30 seconds after dropping), and the result was obtained or the result was graphed. In this measurement, as a liquid having various surface tensions, a wetness index standard solution manufactured by Junsei Chemical Co., Ltd. can be used.
[0038]
By the way, the core layer of the optical waveguide is required to have a higher refractive index than other layers in contact therewith. The other layer in contact with the core layer is usually called a clad layer, and in the present invention, the upper clad layer and the photocatalyst-containing layer correspond to this clad layer. That is, in the present invention, the photocatalyst containing layer can be used as a clad layer. In the present invention, the photocatalyst containing layer may be a lower clad layer to distinguish it from the upper clad layer.
[0039]
Thus, in order to function as a clad layer, in the present invention, the refractive index of the photocatalyst-containing layer is in the range of 1.1 to 1.7, preferably in the range of 1.1 to 1.5. It is preferable.
[0040]
The difference in refractive index between the photocatalyst-containing layer and the core layer is preferably 0.03 or more, particularly 0.05 or more, and particularly preferably 0.1 or more. In general, in an optical waveguide, a cladding layer is a layer whose main purpose is to reflect light guided in the core layer. That is, this layer has a function of preventing absorption loss caused by light guided in the core layer being absorbed by the material constituting the cladding layer. In order to exert such an effect, it is necessary to make the refractive index of the core layer higher than the refractive index of the cladding layer. Therefore, in the present invention, the photocatalyst-containing layer functions sufficiently as a cladding layer by setting the difference in refractive index between the photocatalyst-containing layer and the core layer within the above range.
[0041]
The photocatalyst-containing layer of the present invention is preferably composed of at least a photocatalyst and a binder. By using such a layer, it is possible to change the chemical structure of the binder from the action of the photocatalyst due to energy irradiation, thereby increasing the critical surface tension of the energy irradiated part and reducing the contact angle with the liquid. Can do it.
[0042]
In such a photocatalyst-containing layer, the action mechanism of a photocatalyst represented by titanium oxide as described later is not necessarily clear, but a carrier generated by irradiation with light or the like directly reacts with a nearby compound, Alternatively, it is considered that the active oxygen species generated in the presence of oxygen and water change the chemical structure of the organic matter.
[0043]
In the present invention, the photocatalyst is used to lyophilic by changing the wettability of the exposed area using the action of oxidation, decomposition, etc. of the organic groups and additives that are part of the binder, and wetting with the non-exposed area. It can make a big difference in sex. Therefore, by improving the acceptability (lyophilicity) and the repellent property (liquid repellency) with the coating liquid for forming the core layer, it is possible to obtain an optical waveguide having good quality and advantageous in terms of cost.
[0044]
Further, when such a photocatalyst containing layer is used in the present invention, the photocatalyst containing layer contains at least a photocatalyst and fluorine, and the fluorine content on the surface of the photocatalyst containing layer irradiates the photocatalyst containing layer with energy. In this case, the photocatalyst-containing layer may be formed so as to be lower than that before energy irradiation due to the action of the photocatalyst.
[0045]
In the photocatalyst-containing layer having such characteristics, it is possible to easily form a pattern composed of a portion having a small fluorine content by pattern irradiation with energy. Here, fluorine has an extremely low surface energy. Therefore, the surface of a substance containing a large amount of fluorine has a smaller critical surface tension. Therefore, the critical surface tension of the portion having a small fluorine content is larger than the critical surface tension of the surface of the portion having a large fluorine content. This means that the portion with a low fluorine content is a lyophilic region compared to the portion with a high fluorine content. Therefore, forming a pattern composed of a portion having a lower fluorine content than the surrounding surface forms a pattern of a lyophilic region in the liquid repellent region.
[0046]
Therefore, when such a photocatalyst-containing layer is used, the pattern of the lyophilic region can be easily formed in the lyophobic region by irradiating the pattern with energy. Thus, it is possible to easily form the core layer, and it is possible to obtain an optical waveguide with good quality.
[0047]
As described above, the fluorine content contained in the fluorine-containing photocatalyst containing layer is a portion where the fluorine content in the lyophilic region having a low fluorine content formed by energy irradiation is not irradiated with energy. When the fluorine content is 100, it is preferably 10 or less, preferably 5 or less, particularly preferably 1 or less.
[0048]
By setting it within such a range, it is possible to make a large difference in lyophilicity between the energy-irradiated portion and the unirradiated portion. Therefore, by forming the core layer on such a photocatalyst-containing layer, it becomes possible to form the core layer accurately only in the lyophilic region having a reduced fluorine content, and to obtain a highly accurate optical waveguide. Because you can. This rate of decrease is based on weight.
[0049]
For the measurement of the fluorine content in the photocatalyst-containing layer, various commonly used methods can be used. For example, X-ray photoelectron spectroscopy (ES-ray photoelectron spectroscopy, ESCA) for Chemical Analysis)), and any method that can quantitatively measure the amount of fluorine on the surface, such as X-ray fluorescence analysis and mass spectrometry, is not particularly limited.
[0050]
Examples of the photocatalyst used in the present invention include titanium oxide (TiO 2), which is known as an optical semiconductor.₂), Zinc oxide (ZnO), tin oxide (SnO)₂), Strontium titanate (SrTiO)₃), Tungsten oxide (WO₃), Bismuth oxide (Bi₂O₃), And iron oxide (Fe₂O₃1) or a mixture of two or more selected from these.
[0051]
In the present invention, titanium oxide is particularly preferably used because it has a high band gap energy, is chemically stable, has no toxicity, and is easily available. Titanium oxide includes anatase type and rutile type, and both can be used in the present invention, but anatase type titanium oxide is preferable. Anatase type titanium oxide has an excitation wavelength of 380 nm or less.
[0052]
Examples of such anatase-type titanium oxide include hydrochloric acid peptizer-type anatase-type titania sol (STS-02 manufactured by Ishihara Sangyo Co., Ltd. (average particle size 7 nm), ST-K01 manufactured by Ishihara Sangyo Co., Ltd.), nitric acid solution An anatase type titania sol (TA-15 manufactured by Nissan Chemical Co., Ltd. (average particle size 12 nm)) and the like can be mentioned.
[0053]
The smaller the particle size of the photocatalyst, the more effective the photocatalytic reaction occurs. The average particle size is preferably 50 nm or less, and it is particularly preferable to use a photocatalyst of 20 nm or less. Further, the smaller the particle size of the photocatalyst, the smaller the surface roughness of the formed photocatalyst-containing layer, which is preferable. When the particle size of the photocatalyst exceeds 100 nm, the centerline average surface roughness of the photocatalyst-containing layer becomes coarse, and the photocatalyst The liquid repellency of the non-exposed part of the containing layer is lowered, and the lyophilic expression of the exposed part becomes insufficient.
[0054]
In the present invention, as described above, the surface of the photocatalyst containing layer is made to contain fluorine, and the surface of the photocatalyst containing layer is irradiated with energy to reduce the fluorine content on the surface of the photocatalyst containing layer. An optical waveguide obtained by forming a pattern of a lyophilic region therein and forming a core layer therein may be used. Even in this case, it is preferable to use titanium dioxide as described above as the photocatalyst. However, when titanium dioxide is used in this way, the fluorine content contained in the photocatalyst-containing layer is X-ray photoelectron. When analyzed and quantified by spectroscopy, when the titanium (Ti) element is defined as 100, the fluorine (F) element is in a ratio of 500 or more, preferably 800 or more, particularly preferably 1200 or more. It is preferable that the element is contained on the surface of the photocatalyst containing layer.
[0055]
Fluorine (F) is included in the photocatalyst-containing layer to such an extent that the critical surface tension on the photocatalyst-containing layer can be sufficiently lowered, so that the liquid repellency on the surface can be secured, thereby irradiating energy with the pattern This is because the difference in wettability with the lyophilic region on the surface in the pattern portion where the fluorine content is reduced can be increased, and the quality of the finally obtained optical waveguide can be improved.
[0056]
Further, in such an optical waveguide, the fluorine content in the lyophilic region formed by pattern irradiation of energy is 50 or less, preferably when the titanium (Ti) element is 100. Is preferably contained in a ratio of 20 or less, particularly preferably 10 or less.
[0057]
If the fluorine content in the photocatalyst-containing layer can be reduced to this extent, sufficient lyophilicity can be obtained to form the core layer, etc., and the liquid repellency of the part that has not been irradiated with the above energy The core layer and the like can be formed with high accuracy due to the difference in wettability with respect to, and an optical waveguide with good quality can be obtained.
[0058]
In the present invention, the binder used in the photocatalyst-containing layer preferably has a high binding energy such that the main skeleton is not decomposed by the photoexcitation of the photocatalyst. Examples include organopolysiloxanes that exhibit high strength by hydrolysis and polycondensation, and (2) organopolysiloxanes that are crosslinked with reactive silicones that are excellent in water repellency and oil repellency.
[0059]
In the case of (1) above, the general formula:
Y_nSiX_(4-n)
(Here, Y represents an alkyl group, a fluoroalkyl group, a vinyl group, an amino group, a phenyl group or an epoxy group, X represents an alkoxyl group, an acetyl group or a halogen. N is an integer from 0 to 3. )
It is preferable that it is the organopolysiloxane which is a 1 type, or 2 or more types of hydrolysis condensate or cohydrolysis condensate of the silicon compound shown by these. Here, the number of carbon atoms of the group represented by Y is preferably in the range of 1 to 20, and the alkoxy group represented by X is a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. preferable.
[0060]
As the binder, polysiloxane containing a fluoroalkyl group can be particularly preferably used. Specifically, one or more of the following hydrocondensation condensates and cohydrolysis condensates of fluoroalkylsilanes can be used. In general, those known as fluorine-based silane coupling agents can be used.
[0061]
CF₃(CF₂)₃CH₂CH₂Si (OCH₃)₃;
CF₃(CF₂)₅CH₂CH₂Si (OCH₃)₃;
CF₃(CF₂)₇CH₂CH₂Si (OCH₃)₃;
CF₃(CF₂)₉CH₂CH₂Si (OCH₃)₃;
(CF₃)₂CF (CF₂)₄CH₂CH₂Si (OCH₃)₃;
(CF₃)₂CF (CF₂)₆CH₂CH₂Si (OCH₃)₃;
(CF₃)₂CF (CF₂)₈CH₂CH₂Si (OCH₃)₃;
CF₃(C₆H₄) C₂H₄Si (OCH₃)₃;
CF₃(CF₂)₃(C₆H₄) C₂H₄Si (OCH₃)₃;
CF₃(CF₂)₅(C₆H₄) C₂H₄Si (OCH₃)₃;
CF₃(CF₂)₇(C₆H₄) C₂H₄Si (OCH₃)₃;
CF₃(CF₂)₃CH₂CH₂SiCH₃(OCH₃)₂;
CF₃(CF₂)₅CH₂CH₂SiCH₃(OCH₃)₂;
CF₃(CF₂)₇CH₂CH₂SiCH₃(OCH₃)₂;
CF₃(CF₂)₉CH₂CH₂SiCH₃(OCH₃)₂;
(CF₃)₂CF (CF₂)₄CH₂CH₂SiCH₃(OCH₃)₂;
(CF₃)₂CF (CF₂)₆CH₂CH₂Si CH₃(OCH₃)₂;
(CF₃)₂CF (CF₂)₈CH₂CH₂Si CH₃(OCH₃)₂;
CF₃(C₆H₄) C₂H₄SiCH₃(OCH₃)₂;
CF₃(CF₂)₃(C₆H₄) C₂H₄SiCH₃(OCH₃)₂;
CF₃(CF₂)₅(C₆H₄) C₂H₄SiCH₃(OCH₃)₂;
CF₃(CF₂)₇(C₆H₄) C₂H₄SiCH₃(OCH₃)₂;
CF₃(CF₂)₃CH₂CH₂Si (OCH₂CH₃)₃;
CF₃(CF₂)₅CH₂CH₂Si (OCH₂CH₃)₃;
CF₃(CF₂)₇CH₂CH₂Si (OCH₂CH₃)₃;
CF₃(CF₂)₉CH₂CH₂Si (OCH₂CH₃)₃;
CF₃(CF₂)₇SO₂N (C₂H₅) C₂H₄CH₂Si (OCH₃)₃
[0062]
This is because the liquid repellency of the non-exposed portion of the photocatalyst containing layer can be greatly improved by using the above-described polysiloxane containing a fluoroalkyl group as a binder.
[0063]
Examples of the reactive silicone (2) include compounds having a skeleton represented by the following general formula.
[0064]
[Chemical 1]

[0065]
However, n is an integer greater than or equal to 2, R¹, R²Each represents a substituted or unsubstituted alkyl, alkenyl, aryl or cyanoalkyl group having 1 to 10 carbon atoms, and 40% or less of the total is vinyl, phenyl or phenyl halide in a molar ratio. R¹, R²Is preferably a methyl group because the surface energy becomes the smallest, and the methyl group is preferably 60% or more by molar ratio. In addition, the chain end or side chain has at least one reactive group such as a hydroxyl group in the molecular chain.
[0066]
In addition to the above organopolysiloxane, a stable organosilicon compound that does not undergo a crosslinking reaction, such as dimethylpolysiloxane, may be mixed in the binder.
[0067]
In the optical waveguide of the present invention, various binders such as organopolysiloxane can be used in the photocatalyst-containing layer. In the present invention, as described above, fluorine is contained in the photocatalyst containing layer containing such a binder and photocatalyst, and the fluorine on the surface of the photocatalyst containing layer is reduced by irradiating energy in a pattern, thereby reducing the liquid repellent region. A lyophilic region may be formed inside. At this time, it is necessary to contain fluorine in the photocatalyst-containing layer. As a method of incorporating fluorine into the photocatalyst-containing layer containing such a binder, a fluorine compound is relatively used for a binder having a high binding energy. Examples thereof include a method of bonding with weak binding energy and a method of mixing a fluorine compound bonded with relatively weak binding energy into the photocatalyst containing layer. By introducing fluorine by such a method, when energy is irradiated, a fluorine bonding site having a relatively low binding energy is first decomposed, and thus fluorine can be removed from the photocatalyst containing layer. is there.
[0068]
Examples of the first method, that is, a method of bonding a fluorine compound with a relatively weak binding energy to a binder having a high binding energy include a method of introducing a fluoroalkyl group as a substituent into the organopolysiloxane. be able to.
[0069]
For example, as described in (1) above, as a method for obtaining an organopolysiloxane, an organopolysiloxane exhibiting high strength can be obtained by hydrolyzing and polycondensing chloro or alkoxysilane, etc. by sol-gel reaction or the like. . Here, in this method, as described above, the above general formula:
Y_nSiX_(4-n)
(Here, Y represents an alkyl group, a fluoroalkyl group, a vinyl group, an amino group, a phenyl group or an epoxy group, X represents an alkoxyl group, an acetyl group or a halogen. N is an integer from 0 to 3. )
An organopolysiloxane is obtained by hydrolyzing or co-hydrolyzing and condensing one or two or more of the silicon compounds represented by formula (1). In this general formula, silicon having a fluoroalkyl group as the substituent Y By synthesizing using a compound, an organopolysiloxane having a fluoroalkyl group as a substituent can be obtained. When an organopolysiloxane having such a fluoroalkyl group as a substituent is used as a binder, the carbon bond portion of the fluoroalkyl group is decomposed by the action of the photocatalyst in the photocatalyst-containing layer when irradiated with energy. Therefore, the fluorine content in the portion where the photocatalyst-containing layer surface is irradiated with energy can be reduced.
[0070]
The silicon compound having a fluoroalkyl group used at this time is not particularly limited as long as it has a fluoroalkyl group, but has at least one fluoroalkyl group, and the carbon number of the fluoroalkyl group A silicon compound in which is 4 to 30, preferably 6 to 20, particularly preferably 6 to 16, is preferably used. Specific examples of such a silicon compound are as described above, and among these, the above silicon compound having a fluoroalkyl group having 6 to 8 carbon atoms, that is, a fluoroalkylsilane is preferable.
[0071]
In the present invention, such a silicon compound having a fluoroalkyl group may be used in combination with the above-mentioned silicon compound having no fluoroalkyl group, and these cohydrolyzed condensates may be used as the organopolysiloxane. In addition, one or two or more silicon compounds having such a fluoroalkyl group may be used, and these hydrolyzed condensates and cohydrolyzed condensates may be used as the organopolysiloxane.
[0072]
In the organopolysiloxane having a fluoroalkyl group thus obtained, among the silicon compounds constituting the organopolysiloxane, the silicon compound having the fluoroalkyl group is 0.01 mol% or more, preferably 0.1%. It is preferable that it is contained in mol% or more.
[0073]
By including this degree of fluoroalkyl group, the liquid repellency on the photocatalyst-containing layer can be increased, and the difference in wettability with the portion that has been made lyophilic by irradiation with energy can be increased. Because.
[0074]
Further, in the method shown in (2) above, an organopolysiloxane is obtained by crosslinking a reactive silicone excellent in water repellency and oil repellency. In this case as well, R in the above general formula is similarly used.¹, R²By making either or both of them a fluorine-containing substituent such as a fluoroalkyl group, it is possible to include fluorine in the photocatalyst-containing layer, and when it is irradiated with energy, it is bonded from a siloxane bond. Since the portion of the fluoroalkyl group having a small energy is decomposed, the content of fluorine on the surface of the photocatalyst-containing layer can be reduced by energy irradiation.
[0075]
On the other hand, as a method for introducing a fluorine compound bonded with energy lower than the binding energy of the binder, for example, when introducing a low molecular weight fluorine compound, for example, a fluorine-based surfactant is mixed. Examples of the method of introducing a high molecular weight fluorine compound include a method of mixing a fluorine resin having high compatibility with the binder resin.
[0076]
In the present invention, the photocatalyst-containing layer can contain a surfactant in addition to the above-mentioned photocatalyst and binder. Specifically, hydrocarbons such as NIKKOLBL, BC, BO, BB series manufactured by Nikko Chemicals Co., Ltd., ZONYL FSN, FSO manufactured by DuPont, Surflon S-141, 145 manufactured by Asahi Glass Co., Ltd., Dainippon Ink Chemical industry Co., Ltd. Megafax F-141, 144, Neos Co., Ltd., Fategent F-200, F251, Daikin Industries Co., Ltd. Unidyne DS-401, 402, 3M Co., Ltd. Fluorado FC-170, Fluorine-based or silicone-based nonionic surfactants such as 176 can be mentioned, and cationic surfactants, anionic surfactants, and amphoteric surfactants can also be used.
[0077]
In addition to the above surfactants, the photocatalyst-containing layer includes polyvinyl alcohol, unsaturated polyester, acrylic resin, polyethylene, diallyl phthalate, ethylene propylene diene monomer, epoxy resin, phenol resin, polyurethane, melamine resin, polycarbonate, Polyvinyl chloride, polyamide, polyimide, styrene butadiene rubber, chloroprene rubber, polypropylene, polybutylene, polystyrene, polyvinyl acetate, polyester, polybutadiene, polybenzimidazole, polyacrylonitrile, epichlorohydrin, polysulfide, polyisoprene, oligomers, polymers, etc. It can be included.
[0078]
The content of the photocatalyst in the photocatalyst containing layer can be set in the range of 5 to 60% by weight, preferably 20 to 40% by weight. The thickness of the photocatalyst-containing layer is preferably in the range of 0.1 to 1 μm, particularly preferably in the range of 0.1 to 0.5 μm, because the photocatalyst-containing layer acts as the lower cladding layer.
[0079]
The photocatalyst-containing layer can be formed by dispersing a photocatalyst and a binder in a solvent together with other additives as necessary to prepare a coating solution, and applying the coating solution. As the solvent to be used, alcohol-based organic solvents such as ethanol and isopropanol are preferable. The application can be performed by a known application method such as spin coating, spray coating, dip coating, roll coating, or bead coating. When an ultraviolet curable component is contained as a binder, the photocatalyst-containing layer can be formed by irradiating with ultraviolet rays and performing a curing treatment.
[0080]
(Core layer)
In general, in an optical waveguide, the core layer is required to have a refractive index higher than that of the cladding layer covering the periphery of the core layer because light is transmitted through the core layer. Furthermore, since the light guided through the core layer is transmitted without delay, it is preferable that the peripheral portion of the core layer has a well-shaped shape. This is because the peripheral portion of the core layer is in a well-defined shape, so that it is possible to prevent optical transmission loss due to an incomplete interface between the core layer and the upper cladding layer in contact with the core layer.
[0081]
In the present invention, the upper clad layer and the photocatalyst-containing layer correspond to the clad layer of the general optical waveguide described above. Therefore, the core layer needs to have a higher refractive index than both layers. The refractive index of the core layer in the present invention can be easily adjusted by changing the core layer forming material to be deposited on the photocatalyst-containing layer. The core layer can have a refractive index suitable for the above.
[0082]
Furthermore, in the present invention, the core layer is formed by utilizing the difference in lyophilic and water-repellent wettability generated by energy irradiation on the photocatalyst-containing layer. In other words, the core layer forming material for forming the core layer has a marked difference in adhesion to the lyophilic region and the water-repellent region. By utilizing this property, the core layer forming material is used only in the lyophilic region. It is possible to deposit material. Therefore, since the peripheral portion of the core layer has a well-defined shape, it is possible to prevent an optical transmission loss due to an incomplete interface between the core layer and the upper cladding layer in contact with the core layer.
[0083]
Examples of the material for forming such a core layer include polyimide, polycarbonate, polymethyl methacrylate, polystyrene, and silicon oxide. These materials are selected from various coating methods such as spin coating method and dip coating method, nozzle ejection methods such as ink jet method, vapor deposition method and electroless plating method according to the characteristics of the material to form the core layer. Further, the refractive index can be controlled by the type of material to be selected and the mixing ratio.
[0084]
In addition, in the optical waveguide, it is necessary to make the refractive index of the core layer higher than the refractive index of the cladding layer covering the surface in order to keep the light guided in the core layer well. In the present invention, the refractive index of the core layer is preferably in the range of 1.1 to 1.7, preferably in the range of 1.4 to 1.7. Furthermore, when the upper clad layer covering the surface of the core layer is formed of a material having transparency, the refractive index difference from the core layer is preferably 0.03 or more, particularly 0.05 or more. By making the difference in refractive index between the core layer and the upper clad layer within the above range and the difference in refractive index between the photocatalyst containing layer and the core layer covering the lower part of the core layer within the above range, optical transmission loss is small. An optical waveguide can be manufactured.
[0085]
Here, the shape of the core layer is usually determined in consideration of the mode of light guided in the core layer. Since the infrared light is generally used as the guided light, the film thickness from the top to the bottom of the core layer is preferably in the range of 0.8 to 300 μm, and preferably in the range of 1 to 100 μm. Further, the width of the bottom of the core layer is preferably in the range of 0.8 to 300 μm, preferably in the range of 1 to 100 μm. This is because, by setting the core layer within the above range, light can be guided through the core layer without delay, and an optical waveguide with good efficiency can be obtained.
[0086]
(Upper cladding layer)
In the present invention, the upper cladding layer 5 is formed so as to cover the surface of the core layer 4 as shown in FIG. The upper clad layer 5 shown in FIG. 1 is formed on the entire surface of the photocatalyst-containing layer 2, but may be an upper clad layer formed in a pattern so as to cover the surface of the core layer. Also, the role of the cladding layer in the optical waveguide is to reduce the optical transmission loss of the optical waveguide, to prevent adverse effects due to external stress, etc., and to cut the end face of the optical waveguide and polish the end face For example, it is possible to perform precision machining.
[0087]
In the present invention, the upper clad layer may be in any form of being formed of a transparent material and opaque.
[0088]
First, the case where the upper cladding layer is formed of a transparent material will be described.
[0089]
Examples of the material used when the upper clad layer is made of a transparent material include, for example, silicon resin, polymethacrylate resin, polycarbonate resin, silicon oxide, UV curable epoxy resin, epoxy resin, fluorinated polyimide, Examples thereof include polyimide, polycarbonate-MMA, deuterated polyfluoromethacrylate and the like.
[0090]
These materials can be attached by, for example, a vapor deposition method, but are preferably applied by various coating methods such as spin coating, spray coating, dip coating, roll coating, bead coating, and ejection methods such as inkjet. The upper clad layer is formed by applying the above material as a liquid. In addition, since the refractive index can be easily changed depending on the type of material to be selected and the mixing ratio of the materials, it is possible to form an upper cladding layer in which the refractive index difference is controlled according to the refractive index of the core layer.
[0091]
In the present invention, the refractive index of the upper cladding layer is preferably in the range of 1.1 to 1.7, and preferably in the range of 1.4 to 1.7. This is because by setting the upper clad layer within the above range, it is possible to effectively prevent absorption loss, which is one factor of optical transmission loss.
[0092]
Further, the difference in refractive index between the upper cladding layer and the core layer is preferably 0.03 or more, more preferably 0.05 or more. This is because if the refractive index of the core layer is higher than the refractive index of the upper cladding layer within the above range, an optical transmission loss due to an absorption loss can be efficiently prevented and an optical waveguide having a good transmission efficiency can be manufactured.
[0093]
By the way, as described above, in the present invention, the shape of the upper clad layer may be formed on the entire surface of the photocatalyst-containing layer, or may be formed in a pattern so as to cover the core layer surface. is there.
[0094]
As shown in FIG. 1, when the upper clad layer is formed on the entire surface of the photocatalyst containing layer, there is an advantage that it is relatively easy to manufacture. Furthermore, when the upper cladding layer is formed on the entire surface of the photocatalyst-containing layer and has transparency, the thickness of the upper cladding layer from the top of the core layer to the surface of the upper cladding layer is in the range of 0.5 to 300 μm. Among them, it is particularly preferable that the thickness is in the range of 1 to 100 μm. This is because when the film thickness is thinner than the above range, the loss of light guided through the core layer is remarkably increased, and the film does not function as an optical waveguide.
[0095]
On the other hand, the upper clad layer may be formed in a pattern so as to cover the core layer on the photocatalyst containing layer. By forming the upper clad layer in a pattern in this way, a complicated optical wiring is applied on the planar substrate, and a planar optical waveguide having an optical interconnection function such as branching, switching, and connection is obtained with low loss. This is because it has an advantage that it can be easily manufactured.
[0096]
Furthermore, when the upper cladding layer is formed in a pattern and made of a material having transparency, the thickness of the upper cladding layer from the top of the core layer to the top of the upper cladding layer is 0.5 to 300 μm. Within the range, in particular, the range of 1 to 100 μm is particularly preferable. In this case, the upper cladding layer is formed to have a predetermined width on both sides of the core layer, and the width of the upper cladding layer from the side of the core layer to the side of the upper cladding layer is 0.5 to 300 μm. It is preferable that it is in the range of 1-100 micrometers especially among these. If the upper clad layer is formed with a film thickness and width within the above range, the light guided in the core layer is reflected, the core layer is protected from dust and dirt from the surface, external stress, etc. This is because the function as a clad layer that prevents the influence from the above can be sufficiently exhibited.
[0097]
Next, the case where the upper cladding layer is opaque will be described. In this case, the interface between the upper cladding layer and the core layer is preferably made of a metal that acts as a mirror surface. Specific examples of such a metal include gold, aluminum, copper, silver and the like, and aluminum is particularly preferable among them in the present invention. By forming these metals using a vapor deposition method or the like and forming an upper clad layer, the interface between the upper clad layer and the core layer acts as a mirror surface and totally reflects light guided in the core layer. This is because light absorption loss to the upper clad layer is suppressed, and an efficient optical waveguide with less optical transmission loss can be obtained.
[0098]
As for the shape of the upper clad layer, if both are in contact with each other at the interface between the core layer and the upper clad layer, the mirror effect at the interface can be sufficiently obtained. Therefore, the above-described film thickness when the upper clad layer is formed over the entire surface, and the above-described film thickness and width when the upper clad layer is formed in a pattern do not affect this mirror effect. When the upper clad layer is opaque, the film thickness and width of the upper clad layer may be such that there is no problem in total reflection of light.
[0099]
(substrate)
In the present invention, the substrate plays a role as a support and also has a function of reducing the influence on the core layer due to external stress. Although it will not specifically limit if it is a material which bears such a function, Specifically, glass substrates, such as soda glass, quartz glass, optical glass, an alkali free glass, and polycarbonate, a methylmethacrylate homopolymer or copolymer, polyethylene Examples thereof include plastic films such as terephthalate and polystyrene, and plastic sheets.
[0100]
B. About optical waveguide manufacturing method
The method for producing an optical waveguide of the present invention includes a step of preparing a substrate, and at least a photocatalyst and a binder on the substrate, and energy irradiation changes the wettability of the irradiated portion in a direction in which the contact angle with the liquid decreases. A step of forming a photocatalyst-containing layer, a step of irradiating the core layer forming part, which is a part for forming a core layer on the photocatalyst-containing layer, with pattern irradiation of energy to form a core layer exposed part, and Forming a core layer on the exposed portion of the core layer, and forming an upper clad layer on the photocatalyst-containing layer so as to cover the surface of the core layer formed on the photocatalyst-containing layer. Irradiating the upper clad layer forming portion, which is a layer forming portion, with energy to form an upper clad layer exposed portion, and forming an upper clad layer on the upper clad layer exposed portion Those with a degree.
[0101]
In the present invention, such a manufacturing method has an advantage that it is possible to simplify the labor for patterning the core layer, compared to the conventional manufacturing method of the optical waveguide shown in FIG. .
[0102]
FIG. 2 is a process diagram showing an example of a method of manufacturing an optical waveguide according to the present invention. First, each step of FIG. 2 will be described.
[0103]
As shown to (a) of FIG. 2, the board | substrate 1 is prepared, the coating liquid which melt | dissolved the formation material of the photocatalyst containing layer which consists of a photocatalyst and a binder at least on the prepared board | substrate 1 is apply | coated, and it dries. The photocatalyst containing layer 2 is formed (photocatalyst containing layer forming step).
[0104]
Next, a mask 6 is applied to a part other than the core layer forming part which is a part for forming the core layer 4 on the photocatalyst containing layer 2, and pattern irradiation is performed so that energy 7 is irradiated only to the core layer forming part (FIG. 2 ( b)), the core layer exposure part 3 which is an energy irradiation area | region by the said pattern irradiation is formed (core layer exposure part formation process) (FIG.2 (c)).
[0105]
Further, a core layer forming material is attached on the core layer exposure part 3 of the photocatalyst containing layer 2 and dried to form the core layer 4 (core layer forming step) (FIG. 2D).
[0106]
In order to form the upper clad layer 5 so as to cover the surface of the core layer 4 formed on the photocatalyst containing layer 2, the upper clad which is a part where the upper clad layer 5 on the photocatalyst containing layer 2 is formed By irradiating the layer forming portion with energy (FIG. 2 (f)), as shown in FIG. 2 (e), the upper clad layer exposed portion 8 is formed (upper clad layer exposed portion forming step).
[0107]
Then, an upper clad layer forming material is deposited on the upper clad layer exposure portion 8 and dried to form the upper clad layer 5 (upper clad layer forming step) (FIG. 2E).
[0108]
Hereinafter, each of these steps will be described in detail.
[0109]
(Photocatalyst-containing layer forming step)
First, the process of providing the photocatalyst containing layer that is the first process will be described. The photocatalyst-containing layer forming step is a step of forming a photocatalyst-containing layer having at least a photocatalyst and a binder on the substrate and changing the wettability of the irradiated portion in the direction in which the contact angle with the liquid is lowered by energy irradiation.
[0110]
The photocatalyst-containing layer is formed by preparing a coating liquid in which a photocatalyst and a binder as described above are dispersed in a solvent together with other additives as necessary, and applying this coating liquid, followed by hydrolysis, It is formed by advancing the condensation reaction to firmly fix the photocatalyst in the binder. As the solvent to be used, alcohol-based organic solvents such as ethanol and isopropanol are preferable, and coating can be performed by a known coating method such as spin coating, spray coating, dip coating, roll coating, and bead coating. Further, in the case where an ultraviolet curable component is contained as a binder, the photocatalyst-containing layer can be formed on the substrate by performing a curing treatment by irradiating with ultraviolet rays.
[0111]
(Core layer exposed part forming step)
Next, the formation process of the core layer exposure part which is a 2nd process is demonstrated. The core layer exposed portion forming step is a step of forming a core layer exposed portion by pattern irradiating energy to the core layer forming portion which is a portion where the core layer on the photocatalyst containing layer is formed.
[0112]
As the energy irradiated in the present invention, any energy can be used as long as it changes the wettability of the photocatalyst containing layer, but it is preferable to use light. This is because light is easy to control and can be operated safely.
[0113]
Furthermore, it is preferable to use light selected in consideration of the wavelength of light that causes the catalytic reaction of the photocatalyst used in the present invention. For example, cadmium sulfide has a visible light of 496 nm and iron oxide has a light of 539 nm, and titanium dioxide has an ultraviolet light of 388 nm. Thus, in correspondence with the photocatalyst used, visible light or ultraviolet light can be used. However, as described above, it is effective as a photocatalyst because of its high band gap energy, and chemical. In view of the fact that titanium dioxide is suitably used as the photocatalyst because it is stable, non-toxic and easily available, it is preferably light containing ultraviolet light that initiates the catalytic reaction of titanium dioxide. Specifically, it is preferable that ultraviolet light in a range of 400 nm or less, preferably 380 nm or less is included.
[0114]
Examples of light sources including such ultraviolet light include various ultraviolet light sources such as mercury lamps, metal halide lamps, xenon lamps, and excimer lamps. In addition, the light irradiation amount at the time of exposure can be set to an irradiation amount necessary for the exposed portion to exhibit lyophilicity by the action of the photocatalyst.
[0115]
If pattern irradiation is required for energy irradiation, it can be performed by pattern irradiation through a photomask using a light source as described above. As another method, a pattern is formed using a laser such as excimer or YAG. It is also possible to use a drawing irradiation method.
[0116]
The details of the part where the core layer exposure part is formed are as follows. Since it is as having demonstrated in the item of (core layer) about an optical waveguide, description here is abbreviate | omitted.
[0117]
(Core layer formation process)
Next, the core layer forming step as the third step will be described. This core layer forming step is a step of forming a core layer on the core layer exposed portion of the photocatalyst-containing layer.
[0118]
In this core layer forming step, in order to form a core layer in the core layer exposed portion, a method of attaching a core layer forming material onto the core layer exposed portion is employed. Examples of this method include a coating method, a discharge method, a vapor deposition method, an electroless plating method, and the like. Among these methods, a coating method using a coating liquid and a discharge method are preferable.
[0119]
Specifically, the core layer forming material is dispersed in a solvent to prepare a core layer forming coating solution, and this core layer forming coating solution is applied onto the exposed portion of the core layer and then cured. A method for forming the core layer by performing the above can be mentioned. Further, among the methods using this coating solution, the nozzle discharge method is preferred from the viewpoint that the core layer forming coating solution can be efficiently applied. This is because if the nozzle discharge method is used, the application position of the core layer forming coating liquid is accurate, and the amount of the core layer forming coating liquid remaining in the liquid-repellent region can be suppressed. Of these nozzle ejection methods, the ink jet method is preferably used. This is because it is advantageous in terms of cost because it can be mass-produced.
[0120]
As a solvent for dissolving the core layer forming material, a solvent capable of dissolving the core layer forming material and having a contact angle difference of 20 ° or more between the energy exposed portion and the energy unexposed portion of the photocatalyst-containing layer. If it is, it will not specifically limit. In particular, N-methyl-2-pyrrolidone, cyclohexanone and a mixed solution containing these are preferable. Further, when the binder contains an ultraviolet curable component, the core layer can be formed on the exposed portion of the core layer of the photocatalyst-containing layer by performing a curing treatment by irradiating with ultraviolet rays. .
[0121]
(Upper clad layer exposed portion forming step and upper clad layer forming step)
The upper clad layer exposed portion forming step is to form an upper clad layer on the photocatalyst containing layer so as to cover the surface of the core layer formed on the photocatalyst containing layer. In this process, the upper clad layer exposed portion is irradiated with energy to form the upper clad layer exposed portion.
[0122]
Further, the upper clad layer forming step is a step of forming an upper clad layer on the upper clad layer exposed portion.
[0123]
In the present invention, the series of steps of the upper clad layer exposed portion forming step and the upper clad layer forming step can be roughly divided into two embodiments. In the first embodiment, the upper cladding layer is formed of a material having transparency. The second embodiment is a case where the upper cladding layer is opaque. Both embodiments will be described below for each step.
[0124]
a. First embodiment
In the first embodiment, the upper clad layer is formed of a material having transparency. Furthermore, in the first embodiment, due to the difference in the shape of the upper cladding layer,
When the upper cladding layer is formed on the entire surface of the photocatalyst containing layer so as to cover the core layer
When the upper cladding layer is formed in a pattern so as to cover only the surface of the core layer
Can be divided into
[0125]
Hereinafter, the first embodiment will be described for each case of (1) and (2).
[0126]
(1) When the upper clad layer is formed on the entire surface of the photocatalyst containing layer so as to cover the core layer
First, the case where the upper clad layer is formed on the entire surface of the photocatalyst containing layer so as to cover the core layer will be described.
[0127]
Specifically, in the upper clad layer exposed portion forming step, in this case, the entire surface of the photocatalyst-containing layer is irradiated with energy to form an upper clad layer exposed portion (upper clad layer). And the upper clad layer forming step includes forming an upper clad layer on the entire surface so as to cover the core layer on the upper clad layer exposed portion (upper clad layer full surface forming step); Become.
[0128]
Both steps will be described below.
[0129]
(Upper clad layer exposed area entire surface formation process)
The upper clad layer exposed portion entire surface forming step is a step of irradiating energy on the entire surface of the photocatalyst containing layer in which the core layer is formed at a desired position on the photocatalyst containing layer by the core layer forming step. By this energy irradiation, the entire surface of the photocatalyst-containing layer other than the portion where the core layer is formed becomes lyophilic, and this lyophilic region becomes the upper clad layer whole surface exposed portion. Others related to energy irradiation and the like are as described in the core layer exposure portion forming step, and thus description thereof is omitted here.
[0130]
(Upper clad layer whole surface formation process)
In the upper clad layer whole surface forming step, an upper clad layer forming material is attached on the upper clad layer whole surface exposed portion formed in the upper clad layer exposed portion whole surface forming step, and the upper clad layer is formed on the entire surface of the photocatalyst containing layer. Is a step of forming.
[0131]
Examples of a method for adhering such an upper clad layer forming material on the entire exposed surface of the upper clad layer include a coating method, a discharge method, a vapor deposition method, and an electroless plating method. The method and the discharge method are preferable.
[0132]
Specifically, the upper clad layer forming material is dispersed in a solvent to prepare an upper clad layer forming coating solution, and this coating solution is applied on the upper clad layer whole surface exposed portion, Examples include a method of forming a core layer by curing.
[0133]
Here, as the solvent for dissolving the upper clad layer forming material, the upper clad layer forming material can be dissolved, and the difference in the contact angle between the energy exposed portion and the energy unexposed portion of the photocatalyst containing layer is 20 The solvent is not particularly limited as long as it is a solvent having a temperature of 0 ° or more. In particular, N-methyl-2-pyrrolidone, cyclohexanone and a mixed solution containing these are preferable.
[0134]
When the binder contains an ultraviolet curable component, the upper cladding layer can be formed on the entire surface of the photocatalyst-containing layer by irradiating with ultraviolet rays and performing a curing treatment.
[0135]
(2) When the upper cladding layer is formed in a pattern so as to cover only the surface of the core layer
Next, the case where the upper cladding layer is formed of a transparent material and the upper cladding layer is formed in a pattern so as to cover the surface of the core layer will be described.
[0136]
In this case, specifically, in the upper clad layer exposed portion forming step, the surface of the photocatalyst containing layer is irradiated with a pattern of energy so as to have a predetermined width on both sides of the core layer, A pattern is formed so as to form a clad layer exposed portion (patterned upper clad layer exposed portion forming step), and the upper clad layer forming step covers the core layer on the patterned upper clad layer exposed portion. This is a step of forming an upper clad layer in a shape (patterned upper clad layer forming step).
[0137]
Both steps will be described below.
[0138]
(Pattern-shaped upper clad layer exposure part forming process)
The patterned upper clad layer exposed portion forming step is a step of pattern irradiating energy on the photocatalyst-containing layer having the core layer at a desired position by the core layer forming step.
[0139]
In this step, the photocatalyst-containing layer in the region from the side of the core layer to a certain width is irradiated with a pattern so that the region from the side of the core layer to the certain width surrounds the core layer. It becomes a lyophilic region. This lyophilic region is the patterned upper clad layer exposure portion. In addition, since the width from the core layer side portion to the upper clad layer side portion, the energy irradiation method, and the like are as described above, description thereof is omitted here.
[0140]
(Pattern upper clad layer forming process)
The patterned upper clad layer forming step is a step of forming an upper clad layer on the patterned upper clad layer exposed portion formed in the patterned upper clad layer exposed portion forming step.
[0141]
This pattern-like upper clad layer forming step is the same as the above-described upper clad layer entire surface forming step except that the upper clad layer is formed in a pattern, and thus detailed description thereof is omitted here.
[0142]
b. Second embodiment
In the second embodiment of the present invention, the upper cladding layer is formed of an opaque material.
[0143]
As described above, since the interface between the core layer and the upper clad layer needs to act as a mirror surface as described above, the manufacturing method when the upper clad layer is formed of an opaque material is specifically described. Examples of the method include a vapor deposition method, a sputtering method, a CVD method, a transfer method, an electroless plating method, a coating method using spray coating using a molten metal, and the like.
[0144]
In this case, as long as a metal is formed without a gap at the interface between the core layer and the upper cladding layer, total reflection of light by the effect of the specular effect is efficiently performed. Therefore, as described above, even when the upper cladding layer is formed on the entire surface of the photocatalyst-containing layer or in a pattern, the upper cladding layer has no gap at the interface between the core layer and the upper cladding layer. As long as is formed, total reflection of light by this mirror effect occurs. Therefore, it is preferable to form the above-described metal used when the upper cladding layer is opaque to the extent that the mirror effect is not impaired by the above-described method.
[0145]
The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.
[0146]
【Example】
The following examples further illustrate the invention.
[0147]
A photocatalyst-containing layer containing a photocatalyst is formed on a 50 × 100 mm non-alkali glass substrate, and ultraviolet rays are irradiated through a mask pattern provided with a line pattern having an opening line width of 100 μm. Patterns with different wettability according to the line pattern were formed.
[0148]
When a N-methyl-2-pyrrolidone solution of polymethyl methacrylate was applied by a dispenser method of a 100 μm line pattern forming portion which is an energy exposure portion of a substrate having this pattern, the solution adhered only to the energy exposure portion. . This was cured by drying at 250 ° C. for 30 minutes.
[0149]
Next, the entire substrate was exposed to ultraviolet light, and a cyclohexanone solution of polystyrene was applied to the entire surface of the substrate. By curing this by the same drying method as described above, an optical waveguide with an optical loss of 30 dB / m or less could be formed.
[0150]
【The invention's effect】
According to the present invention, the core layer forming part on the photocatalyst-containing layer is made lyophilic in advance, and the core layer forming coating liquid is attached only to the lyophilic region having a small contact angle with the liquid, There is an effect that the core layer can be accurately produced in a desired region. Furthermore, in the present invention, since the core layer is formed on the photocatalyst-containing layer, the photocatalyst-containing layer has the same function as the upper cladding layer by adjusting the refractive index difference between the core layer and the photocatalyst-containing layer. It can be used as a lower cladding layer. Accordingly, there is no need to separately form a cladding layer, the process can be simplified, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of an optical waveguide of the present invention.
FIG. 2 is a process diagram showing an example of a method of manufacturing an optical waveguide according to the present invention.
FIG. 3 is a process diagram showing a conventional method of manufacturing an optical waveguide.
[Explanation of symbols]
1 ... Substrate
2 ... Photocatalyst containing layer
3 ... Core layer exposure part
4 ... Core layer
5 ... Upper cladding layer

Claims (16)

A substrate, formed on said substrate, at least a photocatalyst and a photocatalyst-containing layer wettability so as to reduce the contact angle with a liquid is made of a binder which changes by the action of the photocatalyst accompanied by the energy irradiation, the photocatalyst-containing layer By irradiating energy on the pattern and forming a lyophilic region in which a core layer is formed on the photocatalyst-containing layer in a pattern, and then applying a coating liquid for forming a core layer on the photocatalyst-containing layer It has a core layer formed in a pattern, and an upper clad layer formed by applying an upper clad layer forming coating solution on the photocatalyst-containing layer so as to cover the core layer Optical waveguide.   The optical waveguide according to claim 1, wherein the upper clad layer is formed in a pattern on the photocatalyst-containing layer.   The contact angle with a liquid having a surface tension of 40 mN / m on the photocatalyst-containing layer is 10 degrees or more in a portion not irradiated with energy and less than 10 degrees in a portion irradiated with energy. The optical waveguide according to claim 1 or 2.   The optical waveguide according to any one of claims 1 to 3, wherein a difference in refractive index between the photocatalyst-containing layer and the core layer is 0.03 or more.   The upper clad layer is made of a transparent material, and the refractive index difference between the upper clad layer and the core layer is 0.03 or more. An optical waveguide according to any one of the claims.   The light according to any one of claims 1 to 4, wherein the upper clad layer is opaque, and an interface between the upper clad layer and the core layer is made of a metal that acts as a mirror surface. Waveguide.   The photocatalyst-containing layer contains fluorine, and when the photocatalyst-containing layer is irradiated with energy, the photocatalyst-containing layer has a fluorine content on the surface of the photocatalyst-containing layer that is reduced by the action of the photocatalyst as compared with that before energy irradiation. The optical waveguide according to any one of claims 1 to 6, wherein a containing layer is formed. The photocatalyst is composed of titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), strontium titanate (SrTiO ₃ ), tungsten oxide (WO ₃ ), bismuth oxide (Bi ₂ O ₃ ), and oxide. The optical waveguide according to any one of claims 1 to 7, wherein the optical waveguide is one or more substances selected from iron (Fe ₂ O ₃ ).   The optical waveguide according to claim 8, wherein the photocatalyst is titanium oxide. The binder is Y _n SiX _(4-n) (wherein Y represents an alkyl group, a fluoroalkyl group, a vinyl group, an amino group, a phenyl group or an epoxy group, X represents an alkoxyl group or a halogen, and n represents It is an integer from 0 to 3.) It is an organopolysiloxane which is one or two or more kinds of hydrolysis condensates or cohydrolysis condensates of silicon compounds represented by The optical waveguide according to any one of claims 9 to 9. Preparing a substrate;
On the substrate, forming a photocatalyst-containing layer having at least a photocatalyst and a binder whose wettability changes so that a contact angle with the liquid is lowered by the action of the photocatalyst accompanying energy irradiation;
A step of forming a core layer exposure part by pattern irradiating energy to a core layer forming part which is a part for forming a core layer on the photocatalyst-containing layer,
Forming a core layer by applying a coating solution for forming a core layer on the exposed portion of the core layer of the photocatalyst-containing layer; and
In order to form an upper clad layer so as to cover the surface of the core layer formed on the photocatalyst containing layer, an upper clad layer forming portion which is a portion where the upper clad layer on the photocatalyst containing layer is formed is formed. Irradiating energy to form an upper clad layer exposed portion;
And a step of forming an upper clad layer by applying an upper clad layer forming coating solution on the upper clad layer exposed portion. Forming the upper clad layer exposed portion by the energy irradiation, and forming the upper clad layer on the upper clad layer exposed portion,
Irradiating the surface of the photocatalyst-containing layer with energy so as to have a predetermined width on both sides of the core layer, and forming an upper clad layer exposed portion;
The method of manufacturing an optical waveguide according to claim 11, further comprising: forming an upper clad layer so as to cover the core layer on the upper clad layer exposed portion. Forming the upper clad layer exposed portion by the energy irradiation, and forming the upper clad layer on the upper clad layer exposed portion,
Irradiating the entire surface of the photocatalyst-containing layer with energy to form an upper clad layer exposed portion;
12. The method of manufacturing an optical waveguide according to claim 11, further comprising a step of forming an upper clad layer so as to cover a core layer on the upper clad layer exposed portion.   The contact angle with a liquid having a surface tension of 40 mN / m on the photocatalyst-containing layer is 10 degrees or more in a portion not irradiated with energy and less than 10 degrees in a portion irradiated with energy. The method for manufacturing an optical waveguide according to any one of claims 11 to 13.   The core layer formed in a pattern on the photocatalyst-containing layer is a core layer formed by applying a coating solution for forming a core layer. The manufacturing method of the optical waveguide as described in the said claim.   16. The method of manufacturing an optical waveguide according to claim 15, wherein the step of applying the core layer forming coating liquid to form the core layer is applied by a nozzle discharge method.

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